OpenXml creates corrupted Excel when there is a large number of rows

Question

I implemented this method to create an Excel spreadsheet using openxml. It works 100% of the time when the number of rows is under around 15000 rows, otherwise the Excel will sometimes come out corrupted with Excel showing a message

The workbook cannot be opened or repaired by Microsoft Excel because it is corrupt

Any explanations please?

    public static SaveResults CreateExcelDocument(Stream excelStream, List<ExportColumns> columns, IEnumerable data, string sheetName)
    {
        SaveResults results = new SaveResults();
        results.Status = SAVE_STATUS.ERROR;

        try
        {
            if ((sheetName == null) || (sheetName.Trim() == ""))
                sheetName = "Report";
        }
        catch { }

        try
        {
            using (SpreadsheetDocument document = SpreadsheetDocument.Create(excelStream, SpreadsheetDocumentType.Workbook))
            {

                // Add a WorkbookPart to the document.
                WorkbookPart workbookPart = document.AddWorkbookPart();
                workbookPart.Workbook = new Workbook();

                // Add a WorksheetPart to the WorkbookPart.
                WorksheetPart worksheetPart = workbookPart.AddNewPart<WorksheetPart>();
                SheetData sheetData = new SheetData();
                worksheetPart.Worksheet = new Worksheet(sheetData);

                // Add Sheets to the Workbook.
                Sheets sheets = document.WorkbookPart.Workbook.AppendChild<Sheets>(new Sheets());

                Sheet sheet = new Sheet()
                {
                    Id = workbookPart.GetIdOfPart(worksheetPart),
                    SheetId = 1,
                    Name = sheetName
                };

                //get the type of the object in the list
                Type myListElementType = data.GetType().GetGenericArguments().Single();

                // Constructing header
                Row row = new Row();

                foreach (ExportColumns exportColumn in columns)
                {
                    if (!string.IsNullOrEmpty(exportColumn.display.Trim()))
                    {
                        row.Append(ConstructCell(exportColumn.display, CellValues.String));
                    }
                }

                // Insert the header row to the Sheet Data
                sheetData.AppendChild(row);


                foreach (var obj in data)
                {
                    row = new Row();

                    foreach (ExportColumns exportColumn in columns)
                    {
                        if (!string.IsNullOrEmpty(exportColumn.display.Trim()))
                        {
                            object cellObject = null;

                            try
                            {
                                if (myListElementType.GetProperty(exportColumn.name) == null)
                                {
                                    cellObject = ((IDictionary<string, object>)obj)[exportColumn.name];
                                }
                                else
                                {
                                    cellObject = myListElementType.GetProperty(exportColumn.name).GetValue(obj);
                                }

                                //if the value is null bad things happen so put in a cell with a null value string
                                if (cellObject == null)
                                {
                                    // create cell with data
                                    row.Append(
                                    ConstructCell(null, CellValues.String)
                                    );
                                    continue;
                                }

                                if (cellObject is DateTime)
                                {
                                    // create cell with data
                                    DateTime dtValue = (DateTime)cellObject;
                                    row.Append(
                                    ConstructCell(dtValue.ToOADate().ToString(), CellValues.String)
                                    );
                                }
                                else if (IsNumber(cellObject))
                                {
                                    // create cell with data
                                    row.Append(ConstructCell(cellObject.ToString(), CellValues.Number));
                                }
                                else
                                {
                                    // create cell with data
                                    row.Append(ConstructCell(SanitizeXmlString(cellObject.ToString()), CellValues.String));
                                }
                            }
                            catch (Exception ex2)
                            {
                                row.Append(ConstructCell(SanitizeXmlString(exportColumn.path.Trim()), CellValues.String));

                            }
                        }
                    }
                    sheetData.AppendChild(row);
                }

                sheets.Append(sheet);

                worksheetPart.Worksheet.Save();
                document.Close();
            }

            results.Status = SAVE_STATUS.OK;
        }
        catch (Exception ex)
        {
            Logger.Exception.Error("Export Error", ex);

            results.Exception = new ExceptionData(ex);
            results.Status = SAVE_STATUS.ERROR;
        }

        return results;
    }

    private static Cell ConstructCell(string value, CellValues dataType)
    {
        return new Cell()
        {
            CellValue = new CellValue(value),
            DataType = new EnumValue<CellValues>(dataType)
        };
    }